This invention relates to compositions of glycerol (glycerin or glycerine) based polymer surface active chemistry and methods of producing the unique chemistry compositions. The unique surface active chemistry is branched and cyclic, and has both alkyl ether and ester functionalities along with a beneficial co-product lactic acid and/or lactate salt as an anti-biodegrading agent. The glycerol-based surface active products from this chemistry are produced in a continuous process using a unique formula under a particular low activity atmospheric environment.
Conventionally, syntheses of polyglycerol alkyl ethers and esters are based on polyglycerols. For synthesizing polyglycerols, glycidol-based synthesis is particularly useful in producing structured or hyperbranched polyglycerols (HBPG) and high molecular weight HBPG, such as those described in U.S. Pat. No. 6,822,068 B2 and US Published Application 2008/282579 A1. Alternatively, glycidol is used to directly react with fatty alcohols to produce polyglycerol alkyl ethers in one step as described in US Patent Application 2009/0239958. Unfortunately these syntheses rely on expensive monomer glycidol which is often so expensive that in many cases their use on an industrial scale is cost prohibitive.
A number of production processes have been developed for synthesis of glycerol-based polyols, particularly polyglycerols, from inexpensive monomer glycerol. However, these syntheses are mostly limited to producing linear or at least mostly linear, low molecular weight polyglycerols (or oligoglycerols). U.S. Pat. No. 2,258,892 describes various reaction conditions for synthesizing polyglycerols at reaction temperature 200 to 260 degrees Celsius employing 1% of a caustic or salt by weight as the catalyst relative to glycerol used, but only oligomeric polyglycerol products were produced (mean molecular weight: 116 to 314 Daltons). In U.S. Pat. No. 5,641,836, 0.12% of LiOH or lithium soaps under nitrogen atmosphere were used. In U.S. Pat. No. 6,620,904 B2 0.1% of calcium hydroxide under vacuum was used. In WO 2007/049950 A2, 1% of a weak acid alkaline metal salt was used. In each of these cases, however, only oligomeric polyglycerols were produced.
Another strategy used in the prior art is the use of small amounts of strong bases. In EP 0719752 B1 1% of sodium hydroxide under vacuum or nitrogen was used. JP 3717193 describes using 0.5% of sodium hydroxide under nitrogen. US Application 2008/306231 A1 describes using 0.3% or 0.4% of KOH. Again however the only major product was oligomeric polyglycerols or olygomeric glycerol-based polyols. Other methods are described in U.S. Pat. Nos. 3,637,774, 4,551,561, and 5,198,532, Chinese Patent Application CN 101186696A and Scientific Article Determination of the Optimum Conditions for the Condensation of Glycerin in the Presence of Potassium Hydroxide, D. A. Zhukov, et al., Zhurnal Prikladoni Khimii, Vol. 57, No. 2, pp. 389-392 (1984). Unfortunately these methods also only produce linear polyglycerols.
Although glycerol is not expensive, the current processes for the glycerol-based condensation polymerizations are often inefficient. The resulting polyols are linear and often have rather low molecular weights. Therefore, etherification or esterification of the polyglycerols only results in linear and relative low molecular weight polyglycerol alky ethers or esters, such as descried in U.S. Pat. No. 2,023,388.
Additionally in prior arts branched or hyperbranched alkyl ethers are produced based on glycerol as described in U.S. Pat. No. 6,683,222 B2, and the structured surface active products are superior to the traditional linear ones in various applications. However, the production requires multiple steps and separations, and use hydrogen peroxide as an epoxidation reagent which is of a safety concern in industrial scale. The process inefficiency and safety concern of the synthesis are limiting factors for scaling up. In US Patent Application 2006/0286032 A1, polyglycerol branched esters are synthesized using branched fatty acid, and are superior to the linear esters in cosmetic applications. However, the branched structured are derived only from the fatty acids used and therefore the esters are dimensionally very limited comparing to the esters synthesized from branched polylgycerols. In addition these prior art methods lack cyclic, crosslinked structures and any anti-biodegrading agents. Thus there is a clear need for and utility in an improved method of synthesizing glycerol-based polymer surface active products. The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. §1.56(a) exists.